Image stabilization control apparatus and method

Abstract

An image stabilization control apparatus comprising: a first receiving unit that receives a translational shake signal that indicates a translational shake in a first direction; a second receiving unit that receives a first rotational shake signal that indicates a rotational shake about a first axis that intersects with the direction of gravity and the first direction; a first calculation unit that finds a first fluctuation range of a gravitational component in the first direction based on the first rotational shake signal; a second calculation unit that finds an amount of shake in the first direction based on the translational shake signal and the first fluctuation range; and a third calculation unit that finds a target value for reducing a shake in the first direction based on the amount of shake found by the second calculation unit.

What is claimed is: 
     
         1 . An image stabilization control apparatus comprising one or more processors and/or circuitry which functions as:
 a first receiving unit that receives a translational shake signal that indicates a translational shake in a first direction;   a second receiving unit that receives a first rotational shake signal that indicates a rotational shake about a first axis that intersects with the direction of gravity and the first direction;   a first calculation unit that finds a first fluctuation range of a gravitational component in the first direction within a predetermined period of time based on the first rotational shake signal;   a second calculation unit that finds an amount of shake in the first direction based on the translational shake signal and the first fluctuation range; and   a third calculation unit that finds a target value for reducing a shake in the first direction based on the amount of shake found by the second calculation unit.   
     
     
         2 . The image stabilization control apparatus according to  claim 1 , wherein the translational shake signal is a signal that indicates acceleration of the translational shake, and the first rotational shake signal is a signal that indicates angular velocity of the rotational shake. 
     
     
         3 . The image stabilization control apparatus according to  claim 1 , wherein the one or more processors and/or circuitry further functions as:
 a fourth calculation unit that finds a second fluctuation range of the translational shake signal, and   wherein the second calculation unit finds the amount of shake in the first direction using the second fluctuation range of the translational shake signal.   
     
     
         4 . The image stabilization control apparatus according to  claim 3 , wherein the second fluctuation range is one of a fluctuation range of acceleration, a fluctuation range of velocity and a fluctuation range of displacement. 
     
     
         5 . The image stabilization control apparatus according to  claim 3 , wherein the second calculation unit finds the amount of shake by multiplying the translational shake signal by a ratio of the first fluctuation range to the second fluctuation range. 
     
     
         6 . The image stabilization control apparatus according to  claim 1 , wherein the second calculation unit finds the amount of shake by finding a radius of gyration of the rotational shake about the first axis based on the first fluctuation range, the translational shake signal and the first rotational shake signal, and multiplying the first rotational shake signal by the radius of gyration. 
     
     
         7 . The image stabilization control apparatus according to  claim 1 , wherein the one or more processors and/or circuitry further functions as:
 a third receiving unit that receives a second rotational shake signal that indicates a rotational shake about a second axis that is orthogonal to the first direction and the first axis;   a fifth calculation unit that finds a third fluctuation range of the second rotational shake signal; and   a determination unit that determines a phase difference between a phase of the first rotational shake signal and a phase of the second rotational shake signal, and   wherein the second calculation unit finds the amount of shake further using the third fluctuation range and the phase difference.   
     
     
         8 . The image stabilization control apparatus according to  claim 1 , wherein the one or more processors and/or circuitry further functions as:
 a third receiving unit that receives a second rotational shake signal that indicates a rotational shake about a second axis that is orthogonal to the first direction and the first axis;   a fifth calculation unit that finds a third fluctuation range of the second rotational shake signal; and   a determination unit that determines a phase difference between a phase of the translational shake signal and a phase of an acceleration component of the gravity in the first direction, and   wherein the second calculation unit finds the amount of shake further using the third fluctuation range and the phase difference.   
     
     
         9 . The image stabilization control apparatus according to  claim 1 , wherein the one or more processors and/or circuitry further functions as:
 a fifth calculation unit that finds a third fluctuation range of the first rotational shake signal; and   a determination unit that determines a phase difference between a phase of the translational shake signal and a phase of an acceleration component of the gravity in the first direction, and   wherein the second calculation unit finds the amount of shake further using the third fluctuation range and the phase difference.   
     
     
         10 . The image stabilization control apparatus according to  claim 7 , wherein the one or more processors and/or circuitry further functions as:
 a fourth calculation unit that finds a second fluctuation range of the translational shake signal, and   wherein the second calculation unit finds, as a fourth fluctuation range, a sum of the first fluctuation range and the second fluctuation range in a case where the phase difference is within a predetermined range and an absolute value of a difference between the first fluctuation range and the second fluctuation range in a case where the phase difference is not within the predetermined range, and finds the amount of shake by multiplying the second rotational shake signal by a radius of gyration of the rotational shake about the second axis, the radius of gyration being obtained by using the fourth fluctuation range and the third fluctuation range.   
     
     
         11 . The image stabilization control apparatus according to  claim 9 , wherein the one or more processors and/or circuitry further functions as:
 a fourth calculation unit that finds a second fluctuation range of the translational shake signal, and   wherein the second calculation unit finds, as a fourth fluctuation range, a sum of the first fluctuation range and the second fluctuation range in a case where the phase difference is within a predetermined range and an absolute value of a difference between the first fluctuation range and the second fluctuation range in a case where the phase difference is not within the predetermined range, and finds the amount of shake by multiplying the first rotational shake signal by a radius of gyration of the rotational shake about the first axis, the radius of gyration being obtained by using the fourth fluctuation range and the third fluctuation range.   
     
     
         12 . The image stabilization control apparatus according to  claim 3 , wherein the one or more processors and/or circuitry further functions as:
 a fifth calculation unit that finds a third fluctuation range of the first rotational shake signal, and   wherein the second calculation unit finds a radius of gyration of a rotational shake converted from the translational shake based on the third fluctuation range and an absolute value of a difference between the first fluctuation range and the second fluctuation range, and finds the amount of shake by multiplying the first rotational shake signal by the radius of gyration.   
     
     
         13 . The image stabilization control apparatus according to  claim 1 , wherein the first fluctuation range is found based on at least one of a root mean square value, an effective value, maximum and minimum values, an area of a waveform, and a discrete Fourier transform value of a predetermined frequency of the gravitational component in the first direction within the predetermined period of time. 
     
     
         14 . The image stabilization control apparatus according to  claim 7 , wherein the one or more processors and/or circuitry further functions as:
 a fourth calculation unit that finds a second fluctuation range of the translational shake signal, and   wherein the translational shake signal is a signal that indicates acceleration of the translational shake,   the fourth calculation unit finds a fluctuation range of an acceleration component of the gravity as the second fluctuation range, and   the fifth calculation unit finds a fluctuation range of angular acceleration as the third fluctuation range by differentiating the second rotational shake signal.   
     
     
         15 . The image stabilization control apparatus according to  claim 7 , wherein the one or more processors and/or circuitry further functions as:
 a fourth calculation unit that finds a second fluctuation range of the translational shake signal, and   wherein the translational shake signal is a signal that indicates acceleration of the translational shake,   the first receiving unit integrates to convert the translational shake signal into a signal indicating velocity, and outputs the signal indicating velocity to the fourth calculation unit,   the fourth calculation unit finds a fluctuation range of the signal indicating velocity as the second fluctuation range,   the first rotational shake signal is a signal indicating angular velocity of the rotational shake, and   the first calculation unit integrates an acceleration component of the gravity to find a fluctuation range of a velocity component as the first fluctuation range.   
     
     
         16 . The image stabilization control apparatus according to  claim 7 , wherein the one or more processors and/or circuitry further functions as:
 a fourth calculation unit that finds a second fluctuation range of the translational shake signal, and   wherein the translational shake signal is a signal that indicates acceleration of the translational shake,   the first receiving unit performs double integration on the translational shake signal to be converted into a signal indicating displacement, and outputs the signal indicating displacement to the fourth calculation unit,   the fourth calculation unit finds a fluctuation range of the signal indicating displacement as the second fluctuation range,   the first rotational shake signal is a signal indicating angular velocity of the rotational shake,   the first calculation unit performs double integration on an acceleration component of the gravity to find a fluctuation range of a displacement component as the first fluctuation range, and   the fifth calculation unit finds a fluctuation range of a signal indicating an angle as the third fluctuation range by integrating the second rotational shake signal.   
     
     
         17 . The image stabilization control apparatus according to  claim 7 , wherein the third receiving unit includes a band-pass filter that extracts a signal of a predetermined frequency, and outputs the second rotational shake signal of the frequency extracted by the band-pass filter. 
     
     
         18 . The image stabilization control apparatus according to  claim 1 , wherein each of the first receiving unit and the second receiving unit includes a band-pass filter that extracts a signal of a predetermined frequency, and the first receiving unit outputs the translation shake signal of the frequency extracted by the band-pass filter and the second receiving unit outputs the first rotational shake signal of the frequency extracted by the band-pass filter. 
     
     
         19 . The image stabilization control apparatus according to  claim 1 , wherein the second receiving unit is capable of receiving signals that indicate rotational shakes about a plurality of axes that intersect with the direction of gravity and the first direction, and
 the first calculation unit selects a signal to be used as the first rotational signal out of the signals that indicate the rotational shakes about the plurality of axes.   
     
     
         20 . An image stabilization control method comprising:
 receiving a translational shake signal that indicates a translational shake in a first direction;   receiving a rotational shake signal that indicates a rotational shake about an axis that intersects with the direction of gravity and the first direction;   finding a fluctuation range of a gravitational component in the first direction within a predetermined period of time based on the rotational shake signal;   finding an amount of shake in the first direction based on the translational shake signal and the fluctuation range; and   finding a target value for reducing a shake in the first direction based on the amount of shake in the first direction.